Wheelchairs of the above kind undoubtedly represent real progress in that they not only provide mobility, which is essential, but also they enable the subject to take up a standing position which is also important to avoid the physical damage that stems from remaining for a long time in the sitting position.
The prior art proposes various solutions for making wheelchairs of the above type. Those various proposals have advantages and drawbacks, but in general they enable a subject to take up a standing posture, at least to some extent.
Nevertheless, it has been observed that such wheelchairs are unsuitable for use by handicapped or invalid subjects who no longer possess sufficient muscle control to maintain a stable position on the plane supporting them in the standing posture and constituted by the raised articulated structure of a wheelchair.
That is why proposals have been made, in particular in French patent 83/08021 (2 545 718) to adapt such wheelchairs by providing them with body-holding devices. One such device comprises a set of means designed to constitute leg pieces engaging the fronts of the subject's legs, and a second set of means constituted by arm-rests capable of being oriented in generally vertical planes in which they form side guards for the body of a sitting subject, and also in a generally horizontal plane in which they constitute respective halves of a chest-retainer for the subject.
Such a device is suitable for enabling the body to be held properly and it can be installed or adapted in a manner that is found to be acceptable.
The means implemented for changing the orientation of the arm-rests need to take account of the requirement for positive locking in each of the two orientations while making it possible to control pivoting from one orientation to the other and back again without requiring significant physical effort.
In the presently known solution, such means make use of a succession of parts and hinge axes that include catches and notches for locking and holding purposes and that are certainly suitable for satisfying the requirements laid down.
However, it has been observed that under certain circumstances that assembly of hinged parts can lead to the fingers being pinched or indeed to clothes being torn or damaged, without forgetting the major risk of breaking or cutting an electrical feed cable extending between a control and, for example, a system for providing electrical assistance in moving to an upright position.
It has therefore been found necessary to propose improvements to the means for hinging the arm-rests and for locking them positively in either of the two orientations, so as to make them suitable for overcoming the above drawbacks.